As many offshore oil rigs reach the end of their life, the need for portable machine tools to assist with decommissioning is set to increase. One example of a difficult challenge faced by decommissioning engineers is the need to sever and lift caissons or casings - often in very difficult and extreme working conditions. Finding the right equipment to carry out these operations efficiently and safely isn’t easy – which is why the Mirage design team have designed three types of casing pin drills for different situations. Let’s take a look at these three machines.
DDU1636 Double Drill Unit
The first of the to be developed was the DDU1636 Casing Pin Drill. The machine incorporates a swing gate, allowing it to be offered to the cylindrical caisson in the open position. The unit is then closed and locked into position with a swing pin and four jaws tightened to hold the unit in position.
The machine allows two lift holes to be drilled simultaneously, with cutter feed applied either manually or using the optional auto-feed. Cutter diameters up to 12” diameter can be used and a 4” cutter is supplied as standard with the machine. The DDU1636 can clamp onto diameters up to 36”, but larger sizes can be made to suit your project.
Horseshoe Double Drill Unit
Unlike the standard double drill unit, the Horseshoe Double Drill Unit remains open on one side when installed in-situ. Instead of locking into position with a swing gate and clamping jaws, the machine uses hydraulically operated clamps at 120 bar pressure to hold it securely in position. The advantage of this method is it can be used where access to one side of the casing is blocked, or when it isn’t safe for an engineer to access that side of the casing. The clamping arms are activated remotely on the machines separate control panel. The unit clamps onto diameters of from 42” up to 63”.
DDI4050 Internal DDU
On some decommissioning jobs, external access simply isn’t possible, or it may not be the most practical way to make the cut. To address this issue, Mirage have designed the DDI (Double Drill Internal unit).
This product shares the same principles as the other double drill units by incorporating two cutters which can operate simultaneously. The feed of the cutters is advanced automatically.
The DDI is offered to the casing and levelled using the height adjustment screws in the top of the machine’s flange. The unit is then secured using the four clamping jaw screws.
The double drill units are commonly used in conjunction with Mirage portable band saws – each of these heavy duty machines are designed to cut through the casings. Together they help towards You can see the BS3248 in action in this video.